On Mai 14 2020, Christian Brauner wrote:
>> static inline pid_t raw_clone(unsigned long flags) {
>> pid_t ret;
>>
>> assert((flags & (CLONE_VM|CLONE_PARENT_SETTID|CLONE_CHILD_SETTID|
>> CLONE_CHILD_CLEARTID|CLONE_SETTLS)) == 0);
>> #if defined(__s390x__) || defined(__s390__) || defined(__CRIS__)
>> /* On s390/s390x and cris the order of the first and second arguments
>> * of the raw clone() system call is reversed. */
>> ret = (pid_t) syscall(__NR_clone, NULL, flags);
>> #elif defined(__sparc__)
>> {
>> /**
>> * sparc always returns the other process id in %o0, and
>> * a boolean flag whether this is the child or the parent in
>> * %o1. Inline assembly is needed to get the flag returned
>> * in %o1.
>> */
>> int in_child, child_pid, error;
>>
>> asm volatile("mov %3, %%g1\n\t"
>> "mov %4, %%o0\n\t"
>> "mov 0 , %%o1\n\t"
>> #if defined(__arch64__)
>> "t 0x6d\n\t"
>> #else
>> "t 0x10\n\t"
>> #endif
>> "addx %%g0, 0, %2\n\t"
>> "mov %%o1, %0\n\t"
>> "mov %%o0, %1" :
>> "=r"(in_child), "=r"(child_pid), "=r"(error) :
>> "i"(__NR_clone), "r"(flags) :
>> "%o1", "%o0", "%g1", "cc" );
>>
>> if (error) {
>> errno = child_pid;
>> ret = -1;
>> } else
>> ret = in_child ? 0 : child_pid;
>> }
>> +#elif defined(__ia64__)
>> + /* On ia64 the stack and stack size are passed as separate arguments. */
>> + return (pid_t)syscall(__NR_clone, flags, NULL, 0);
>> +#else
>> + return (pid_t)syscall(__NR_clone, flags, NULL);
>> +#endif
>
> Scratch that. It's even worse. On ia64 it is _invalid_ to pass a NULL
> stack.
Only if you want CLONE_VM. But this raw_clone does not allow CLONE_VM,
thus it is actually a true fork.
Andreas.
--
Andreas Schwab, schwab@xxxxxxxxxxxxxx
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